European Patent Publication No. EP-A 0,242,290 discloses such an ejector mechanism, wherein the ejector is driven by a pressurized gas produced by a pyrotechnical generator. Rather than producing the pressurized gas by a generator, it is also possible to supply the pressurized gas by means of a high pressure gas bottle. However, the temperature of the pressurized gas entering into the working cylinder depends on the outside temperature. Thus, the temperature of the pressurized gas may vary considerably. Due to the long conduit from the pyrotechnical gas generator to the working cylinder, the produced pressurized gas cools down as a function of the outside temperature so that said cooling may be substantial. Additionally, the cooling of the pressurized gas is subject to substantial variations. When the pressurized gas is supplied by a high pressure bottle, the gas temperation also depends completely on the outside temperature.
However, an ejector mechanism of this type requires a certain well defined energy for performing the ejection. Such energy is determined by the mass of the ammunition body to be ejected.
The energy needed for the ejection is further dependent on the required ejection speed. Thus, the gas generator or the high pressure gas bottle must be so constructed and dimensioned that the required energy will be made available even at the lowest possible temperature, or rather outside temperature under which the mechanism is expected to perform its function. Such minimum temperatures may well be in the range of, for example -50.degree. to -60.degree. C. By satisfying this minimum temperature requirement, the known system normally will provide excess energy when an ammunition body is to be ejected under normal external temperature condition in the range of, for example +40.degree. to +70.degree. C. Thus, the available energy is normally not utilized and the pressure on the ejector piston is unnecessarily large. As a result, the reaction forces that must be taken up can have detrimental effects, for example, on the air frame of an aircraft which must take up these reaction forces.
Another disadvantage of the known mechanism is seen in that the pressurized gas is used up without any recovery so that new pressurized gas must be made available for each successive ejection of an ammunition body from the ammunition carrier.